LSGunZ28

iTrader: (8)

Look, my last thread turned out to be a mess. I want to only include important information and keep it short and sweet as possible...

I want to re use my 5.3 stage 2.5 heads, if you want to ask why, its discussed in my other thread ( https://ls1tech.com/forums/generation-iv-internal-engine/868071-mild-driveable-cam-402-but-want-over-520rwhp.html )... so whats the biggest block I can go that is compatible with these heads... I also want to reuse my caddy lifters, hardened pushrods, 1.7 rockers, etc....

ran through pacesetters, ORYm magnaflow, CAI, lid, K&N, homeportd TB, built T-56, LS7 clutch with aluminum FW, full suspension, Moser 12 bolt 3.73s...

drievability and reliability is a big concern, more than power at this moment. So if Im not gonna make 500whp, so be it. I just want my car back to drive...


after I get this information, I will make a cam choice based on the responses here...

1997bird

iTrader: (2)

This is a cam that I would have ground for myself if I wanted what you are describing:238/242 113+2 .622"/.622". Here is a link to my cousin's 403 build, https://ls1tech.com/forums/dynamometer-results-comparisons/869674-our-latest-403-532-rwhp-491-tq.html .

LSGunZ28

iTrader: (8)

is that a pretty tame cam for a 402?
is it mild to a 402 if a 224/224 114lsa cam is to a LS1?

1997bird

iTrader: (2)

It should be pretty tame with a good tune, as it only has 14* of overlap @0.050" duration. I know that Ed (edcmat-l1) at The HP Factory would be able to make it run like a stock cammed engine. I'm sure that there are others out there that could accomplish this as well but I like to use Ed.

P.S. My cousin has a different cam in his Vette than what I gave to you.

LSGunZ28

iTrader: (8)

I was recommended a 238/240 cam 111lsa + 2 by patrick G...unless I decided to go with heads with bigger valves..

LSGunZ28

iTrader: (8)

these are the heads btw

This all new 5.3l cylinder head program offers smaller sized runners, upgraded valves, & PRC Valve Springs! The all new cylinder head is a result of over 6 months of testing & tweaking in effort to offer the best combination of runner size, and value!

Side by side flow testing has shown over 15cfm improvement over a popular competitors 225cc as cast cylinder head! This cylinder head was designed to be the ultimate in bolt on cylinder head for customers wanting to keep pricing down with stock castings!

Intake Flow Information:

.300 208
.400 257
.500 290
.600 312


The PRC Cylinder Heads Feature:

Brand New GM 5.3l Based Cores
Smaller Combustion Chambers For 10.75:1 Compression
Stainless Steel 2.04"/1.575" Valves
PRC Double Spring Kit Complete With
Springs, Titanium Retainers, Seats, & Seals
Completely Assembled & Setup To Your Specs!

Jantzer98SS

iTrader: (54)

Use your heads, but open the chamber up to whatever bore you plan to use. Pretty simple procedure. That way it unshrouds the valves and doesn't leave the edges of the chamber on the head hanging in the cylinder.

Scott

LSGunZ28

iTrader: (8)

what do you mean "open up the chamber"

and I was talking to Patrick G. I may have a change of heart... I was almost seton a 402, since it was a godo upgrade, was gonna cost almost as much as rebuilding my 346.. But now I know its gonna work with L92 or a LS7... I dunno I just may go with one of those.. and later get better headers, manifold, cam, heads, etc...

lets say I do this, is it worth paying the difference and getting the LS7 vs the L92/LS3? I will not use a stroke longer than 4" on either... since I road race this car..

its 1500 bucks more for a .1" bigger bore and its gonna net me .15 liters more... is it worth it?

LSGunZ28

iTrader: (8)

https://ls1tech.com/forums/generation-iv-external-engine/612758-injectors-l76-intake.html

https://ls1tech.com/forums/generation-iv-internal-engine/499059-ls3-l92-info.html

for personal future use... ^^^^

C&CBird

Are you referring to the block? I don't think the few extra cubes is worth the $$$.

Stang's Bane

iTrader: (22)

That is way too simplistic of a way to look at it.

The best thing that a ls7 block or a lsx block buys you is the larger bore, not the more displacement. The extra displaceement is a nice bonus, but the larger bore is the biggest power "adder". It enables you to run a better (read bigger) cylinder head. You can build a 387 out of a ls7 block with a stock crank, add ls7 heads (or any other big bore head) and as long as you have a stable drivetrain, rev that puppy to the moon and make power.

IMHO the bigger bore is completely worth it, if you have the money.

hammertime

iTrader: (1)

Unless you have to adhere to a max displacement rule for some class you are racing, there is no reason to build a destroked engine. More displacement equals more power, period. Making more power through more RPM is always more expensive while being harder on parts.

Aside from that, the cam required to run at those high rpm's will sacrifice the driveability & reliability that the OP wants out of this combo.

Stang's Bane

iTrader: (22)

I completely agree with everything you said. Maybe I wasn't clear in what I meant.

For a given cylinder head, there is a maximum hp potential. When you raise the displacement of the shortblock underneath it, you effectively lower the rpm range at which it will occur.

What I was trying to say is that the larger bore will allow you to run a larger cylinder head that will move more air, therefore making more hp POSSIBLE.

I believe in displacement also, that is why I have a 427

LSGunZ28

iTrader: (8)

4050 for a 4" bore
4250 for a 4.065" bore( I believe)
5500 or so for a 4.125" bore...

the middle option to me sounds like the best bang for the buck...

unless the LS7 block offers something else that Im overlooking, over the l92...

LSGunZ28

iTrader: (8)

yes I was, but like the other guy said... Its the bigger bore. but still, Im unsure if its worth it.. and I wish the made even a larger bore aluminum block as big as oh lets say.... 4.5" I mean for future engine reference.

Jantzer98SS

iTrader: (54)

Decide how much power is enough and how much you can afford to spend. You can get close to 500rwhp with your 5.3 heads opened up. Here is an extimate for you with a reasonably streetable cam. 402 L92 500rwhp, 402 TFS 520rwhp, 418 L92 510 rwhp, 418 TFS 540rwhp, 427 LS7 550-570ish rwhp, 427 LS7 TFS 600rwhp.

Don't hold me to those numbers, but they are reasonable expections with all the right bolt on parts and supporting mods. The LS7 and TFS really add $ to the equation. The best bang for your buck is probably the 418, although I prefer the extra 9" of the 427 for the same price.

LSGunZ28

iTrader: (8)

this is what I wanna do

Im gonna call texas speed and go with a 418 and use my 5.3 and tv3

but only if they dont accept my 5.3 and tv3 cam back for a set of new heads and a new cam... I wanna see if I can exchange em and ill pay thedifference.. my tv3 and 5.3 heads have less than 120 miles on em. so theyre like brand new...

suppose they accept this, for a 418 wha cam is mild.. im thinking of a 240/244 112 lsa or so cam.. something of that range.. maybe even a couple numbers higher on the duration..

1997bird

iTrader: (2)

Are you going to use the as cast heads or the CNC heads?

LSGunZ28

iTrader: (8)

I thought I mentioned this prefectly clear in all the 3 threads I made..

Im going to use the PRC 5.3 stage 2.5 heads, that have been CNC machined...

I mentioned above the valve sizes as well...

LSGunZ28

iTrader: (8)

Im ordering the 418 from texas speed tomorrow